8:15 AM PT -- We've confirmed Justin Bieber, Katy Perry, Usher and Niall Horan will also be performing.
Sources connected with the event tell us the charity concert will be held at the Old Trafford cricket ground in Manchester ... the same place Beyonce performed last July.
In addition to Coldplay and Miley, Pharrell and Take That will perform at the event headlined by Ariana.
We're told as many as 10 acts will take the stage.
TMZ broke the story, Ariana is returning to Manchester for the concert less than 2 weeks after the terrorist attack at her concert at the Manchester Arena.
Proceeds will go to the victims' families.